Chemical states of arsenic contained in sewage sludge incineration ash and insolubilized material

Journal of Material Cycles and Waste Management - The chemical states of arsenic contained in 4 kinds of sewage sludge incineration ash and insolubilized materials are analyzed using a leaching...     

Development and application of kinetic model on biological anoxic/aerobic filter

An up-flow biological anoxic filter (BANF) has been developed to achieve high removal performance of suspended solids and BOD removal as well as nitrogen. With a view to understand treatment mechanisms, we developed a filtration model that incorporates filtration, deposit scoring and biological reactions simultaneously. The biological reactions consist of four types of reaction; dissolution of organic particles; utilization of dissolved organic matter; denitrification; and self-degradation of bacteria. Whereas the reactor is generally assumed to be a plug flow reactor in the filtration model, it is assumed a continuous-flow stirred tank reactor (CSTR) in the model of biological reactions. The hydrodynamics is supposed that the filter bottom (the portion sludge settled) is a CSTR and the filter bed (the portion filled with filter media) consists of number of CSTR of equal size arranged in series. The model obtained in this study was verified and simulated using experimental results taken from a pilot-scale plant and predicted the experimental data well, applying to design and operate BANF.     

离心脱水机的污泥脱水实验及应用分析

简要阐述了高效型离心脱水机的工作原理及其在上海两个污水处理厂进行的现场污泥脱水实验，结果表明，污泥脱水效果良好，从污泥性状与脱水性分析说明，污泥浓度低，有机物含量高，则脱水性差；有机物含量低，则脱水性好，应用分析表明，随着污泥性状逐年变化，离心脱水机将成为流脱水机。     

Current status and research on E-waste issues in Asia

Rapid economic growth in Asia and the increasing transboundary movement of secondary resources will increasingly require both 3R endeavors (reduce, reuse, recycle) in each country and appropriate control of international material cycles. Recently, managing electrical and electronic waste (E-waste) has become an important target for domestic and international material cycles from the viewpoints of environmental preservation and resource utilization efficiency. To understand the current status of E-waste issues in the context of international material cycles and to discuss the future tasks related to achieving 3R in the region, we organized the National Institute for Environmental Studies (NIES) E-waste Workshop in December 2004. This article reviews past studies on E-waste and briefly describes the topics presented and discussions held at the workshop. The topics at the workshop included E-waste generation, recycling systems, international trade, and environmental impacts. In addition, we discussed various issues such as terminology, current environmental concerns, and possible solutions. Transboundary shipments of E-waste should be conducted taking into consideration the concept of sustainable development. The direction of future research and possible collaborations are also discussed.     

Gas permeability and tortuosity for packed layers of processed municipal solid wastes and incinerator residue.

To make a proper evaluation of gas component movement inside a landfill site, it is important to investigate the different parameters related to gas flow. In this work gas-filled porosity, intrinsic permeability, tortuosity and equivalent pore radius were determined for various packed wastes, such as incineration ash, shredded bulky waste and shredded incombustible waste. These parameters were measured/inferred for samples packed in a column and exposed to a controlled gas flow. The effect of waste conditions, especially the moisture content, on these parameters was also investigated. The intrinsic permeability of such packed wastes was generally in the order of 10(-10) to 10(-9) m2, except for some ash that was one to two orders lower. The tortuosity of waste layer was greater than that of a particulate material and ranged between 2 and 10. The equivalent pore radius was generally in the order of 10(-4) m, which means that gas diffusion is still ordinary in such packed waste layer. The obtained results will be utilized when simulating gas flow inside a landfill site for biogas extraction or site aeration.     

Land-use change and its socio-environmental impact in Eastern Ethiopia’s highland

The Alemaya district (Eastern Ethiopian highlands) is characterized by undulating physiographic features with arid, semi-arid, and humid climatic conditions. This study evaluated socio-environmental changes in land use and land cover during 1985–2011. Screen digitization on remotely sensed data (i.e., Landsat images from 1985 to 2011) was performed to produce 10 classes of land use and land cover. Then, final land-use maps were prepared using a geographic information system following field verification and accuracy assessment. The drying of water bodies, including the prominent lakes Alemaya, Adele, and Tinike, had been the most important environmental change observed. Degraded land, marsh, perennial cropland, and residential areas increased by 37, 438, 42, and 190 %, respectively, whereas grassland, plantation, shrubland, and temporal cropland decreased by 64, 11, 63, and 29 %, respectively. The increase in land degradation (+37 %), the other major observed problem, has made large areas unsuitable for agriculture and has reduced crop productivity. These land-use and land-cover changes have affected both the environment and the livelihoods of local residents; especially the issue related to land degradation requires urgent attention.     

Reuse of secondhand TVs exported from Japan to the Philippines

The trade of secondhand electrical and electronic equipment (EEE) from developed to developing countries has become a growing environmental issue owing to concerns about improper recycling of these goods in developing countries. We followed a 12-m cargo container of cathode-ray-tube color TVs exported from Japan to the Philippines in February 2008. We surveyed the number of TVs damaged in transport, as well as the number of malfunctioning TVs from this shipment. In addition, we present the results of interviews with 113 Filipino consumers who intended to buy secondhand EEE at nine secondhand shops in Metro Manila. Approximately 3% of the imported TVs were damaged upon arrival. The importer sold some of the units directly to local dealers, and kept the rest to repair, refurbish and resell. Approximately 40% of the imported TVs malfunctioned and needed repair in addition to basic reconditioning. Most interviewees indicated that they prefer to buy secondhand EEE because the prices are lower than those of brand-new products. Consumers indicated that they planned on using the product for an average of about 5 years, but the actual period of use may be lower. Most end-of-life EEE in the Philippines is dismantled and recycled by unregulated companies and untrained individuals in markets or near landfill sites, and it is clear that a proper collection system and treatment methods are needed for e-waste. In addition to the material flow of secondhand TVs, we also discuss several economic aspects and appropriate control measures of the international reuse of secondhand TVs.     

北京城区大气干沉降的水溶性离子特征

为了解北京城区大气干沉降中水溶性离子的化学组成与时间变化特征,连续进行了4年多的干沉降采样与分析.结果表明,在222个有效干沉降样品中,存在不同程度的阴离子缺失. SO42-与Ca2+分别是含量最丰富的阴、阳离子组分,其次是NO3-和NH4+. SO42-、NO3-和NH4+呈现相似的季节变化特征,即其浓度在夏季最高,冬季最低. 干沉降基本呈中性,其pH值月变化幅度小,但季节变化明显,夏季低而春季高.     

Ionic composition of TSP and PM2.5 during dust storms and air pollution episodes at Xi'an,China

TSP and PM_2.5 samples were collected at Xi'an, China during dust storms (DSs) and several types of pollution events, including haze, biomass burning, and firework displays. Aerosol mass concentrations were up to 2 times higher during the particulate matter (PM) events than on normal days (NDs), and all types of PM led to decreased visibility. Water-soluble ions (Na⁺, NH₄⁺, K⁺, Mg²⁺, Ca²⁺, F^?, Cl^?, NO₃^?, and SO₄^2?). were major aerosol components during the pollution episodes, but their concentrations were lower during DSs. NH₄⁺, K⁺, F^?, Cl^?, NO₃^?, and SO₄^2? were more abundant in PM_2.5 than TSP but the opposite was true for Mg²⁺ and Ca²⁺. PM collected on hazy days was enriched with secondary species (NH₄⁺, NO₃^?, and SO₄²) while PM from straw combustion showed high K⁺ and Cl^?. Firework displays caused increases in K⁺ and also enrichments of NO₃^? relative to SO₄^2?. During DSs, the concentrations of secondary aerosol components were low, but Ca²⁺ was abundant. Ion balance calculations indicate that PM from haze and straw combustion was acidic while the DSs samples were alkaline and the fireworks' PM was close to neutral. Ion ratios (SO₄^2?/K⁺, NO₃^?/SO₄^2?, and Cl^?/K⁺) proved effective as indicators for different pollution episodes.